Fetopathology and developmental pathology of the embryo and fetus: Duplicitas symmetros

+ Introduction

+ Support

+ Atlas of fetal pathology

+ Congenital malformations of individual organ systems

Duplicitas symmetros

Introduction

Twins are symmetric and relatively well developed, although anomalies are also frequent. Ther are two types of symmetric monsters: disymmetric (planes of symmetry of both parts are at right angles to each other) and monosymmetric.

The difference is that disymetric thoracopagic twins look at each other, while monosymetric twins both look in the same direction.

The possibility for successful surgical separation of such twins depends on the organs shared and other congenital malformations.

Examples: Siamese twins (Chang and Eng Bunker who were xiphopagous) or the Czech Blazek sisters (monosymetric pygopagus).

Classification

Thoracal conjunctions:
- xiphopagus
- sternopagus
- thoracopagus
  - disymmetric form: partially shared trunk, look at each other
  - monosymmetric form: shoulders are fused at angle, arms on the back side may be fused (tribrachius)
  - monosymmetric form has a better prognosis
  - classification according to heart sharing:
    - separate hearts, each in its own pericardium
    - separate hearts sharing one pericardium
    - one heart with atrial union
    - one heart with both atrial and ventricular union
Conjunctions involving the head and trunk:
- prosopothoracopagus
- cephalothoracopagus
Conjunctions involving the pelvis and abdomen:
- ileoxiphopagus
- ileothoracopagus
- pygopagus (dorsal “fusion”)
Monsters with a horizontal axis of symmetry:
- ischiopagus
- craniopagus
- diprosopos
- dicephalus

Case study

Thoracopagus

Marta Ježová

History

11th pregnancy, 7th delivery
the mother has not been examined during the pregnancy
premature, precipitous labour of the twins
vaginal delivery

Macroscopic appearance

male thoracopagus
numerous minor external anomalies and internal organ malformations, some of them shared, the others only in twin A:
- preaxial polydaktyly
- hypospadia
- anomalous gothic palate and hypoplasia of the maxila of the fetus A
- omphalocele
- esophageal atresia and tracheoesophageal fistula in both fetuses
sharing of internal organs:
- shared liver
- partially shared intestines — duodenum and small intestine until the omphaloenteric duct
- shared pericardium
- shared heart in the shape of a wide letter U, externally “fused in the apex region”
the heart:
- shared atrium
- shared ventricles via two muscular defects
  - univentricular heart: left ventricle belongs to the fetus A, right ventricle to the fetus B
  - functionally 4 compartments and 2 rudimental outlet chambers
  - arterial trasposition in fetus A, pulmonary arteries are hypoplastic
  - anomalies of systemic and pulmonary venous return

Thoracopagus (72276)

Thoracopagus, connecting bridge (72289)

Pictures

Thoracopagus, whole view: Thoracopagus, Macro, autopsy (72276) Thoracopagus, Macro, autopsy (72288) Thoracopagus, Macro, autopsy (72287)

Omphalocele: Thoracopagus, Macro, autopsy (72278)

Upper limb malformation: Thoracopagus, Macro, autopsy (72281)

Hypospadia: Thoracopagus, Macro, autopsy (72282)

Missing philtrum, twin A: Thoracopagus, Macro, autopsy (72283)

Twin B: Thoracopagus, Macro, autopsy (72286)

Thoracal conjunction, connecting bridge (shared liver, shared malformed heart): Thoracopagus, Macro, autopsy (72289) Thoracopagus, Macro, autopsy (72290) Thoracopagus, Macro, autopsy (72291) Thoracopagus, Macro, autopsy (72292)

Scheme of the malformed heart: Thoracopagus, scheme of the heart, Macro, autopsy (72303)

Liver, intestine: Thoracopagus, Macro, autopsy (72295) Thoracopagus, Macro, autopsy (72296) Thoracopagus, Macro, autopsy (72297)